<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>websocket::stream::async_read_some (2 of 2 overloads)</title>
<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="../../../../index.html" title="Chapter 1. Boost.Beast">
<link rel="up" href="../async_read_some.html" title="websocket::stream::async_read_some">
<link rel="prev" href="overload1.html" title="websocket::stream::async_read_some (1 of 2 overloads)">
<link rel="next" href="../write.html" title="websocket::stream::write">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td>
<td align="center"><a href="../../../../../../../../index.html">Home</a></td>
<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="overload1.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_read_some.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../write.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload2"></a><a class="link" href="overload2.html" title="websocket::stream::async_read_some (2 of 2 overloads)">websocket::stream::async_read_some
          (2 of 2 overloads)</a>
</h6></div></div></div>
<p>
            Read some message data asynchronously.
          </p>
<h7><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload2.h0"></a>
            <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload2.synopsis"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_read_some.overload2.synopsis">Synopsis</a>
          </h7><pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">class</span> <a href="../../../../../../../../doc/html/boost_asio/reference/MutableBufferSequence.html" target="_top"><span class="emphasis"><em>MutableBufferSequence</em></span></a><span class="special">,</span>
    <span class="keyword">class</span> <a href="../../../../../../../../doc/html/boost_asio/reference/ReadHandler.html" target="_top"><span class="emphasis"><em>ReadHandler</em></span></a> <span class="special">=</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">default_completion_token_t</span><span class="special">&lt;</span>                <a class="link" href="../executor_type.html" title="websocket::stream::executor_type">executor_type</a><span class="special">&gt;&gt;</span>
<a href="../../../../../../../../doc/html/boost_asio/reference/asynchronous_operations.html#boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type" target="_top"><span class="emphasis"><em>DEDUCED</em></span></a>
<span class="identifier">async_read_some</span><span class="special">(</span>
    <span class="identifier">MutableBufferSequence</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">buffers</span><span class="special">,</span>
    <span class="identifier">ReadHandler</span><span class="special">&amp;&amp;</span> <span class="identifier">handler</span> <span class="special">=</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">default_completion_token_t</span><span class="special">&lt;</span> <a class="link" href="../executor_type.html" title="websocket::stream::executor_type">executor_type</a> <span class="special">&gt;{});</span>
</pre>
<h7><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload2.h1"></a>
            <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload2.description"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_read_some.overload2.description">Description</a>
          </h7><p>
            This function is used to asynchronously read some message data. This
            call always returns immediately. The asynchronous operation will continue
            until one of the following conditions is true:
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                Some message data is received.
              </li>
<li class="listitem">
                A close frame is received. In this case the error indicated by the
                function will be <a class="link" href="../../boost__beast__websocket__error.html" title="websocket::error"><code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">closed</span></code></a>.
              </li>
<li class="listitem">
                An error occurs.
              </li>
</ul></div>
<p>
            The algorithm, known as a <span class="emphasis"><em>composed asynchronous operation</em></span>,
            is implemented in terms of calls to the next layer's <code class="computeroutput"><span class="identifier">async_read_some</span></code>
            and <code class="computeroutput"><span class="identifier">async_write_some</span></code>
            functions. The program must ensure that no other calls to <a class="link" href="../read.html" title="websocket::stream::read"><code class="computeroutput"><span class="identifier">read</span></code></a>, <a class="link" href="../read_some.html" title="websocket::stream::read_some"><code class="computeroutput"><span class="identifier">read_some</span></code></a>, <a class="link" href="../async_read.html" title="websocket::stream::async_read"><code class="computeroutput"><span class="identifier">async_read</span></code></a>, or <a class="link" href="../async_read_some.html" title="websocket::stream::async_read_some"><code class="computeroutput"><span class="identifier">async_read_some</span></code></a> are performed
            until this operation completes. Received message data is appended to
            the buffer. The functions <a class="link" href="../got_binary.html" title="websocket::stream::got_binary"><code class="computeroutput"><span class="identifier">got_binary</span></code></a> and <a class="link" href="../got_text.html" title="websocket::stream::got_text"><code class="computeroutput"><span class="identifier">got_text</span></code></a> may be used to query
            the stream and determine the type of the last received message. Until
            the operation completes, the implementation will read incoming control
            frames and handle them automatically as follows:
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                The <a class="link" href="../control_callback.html" title="websocket::stream::control_callback"><code class="computeroutput"><span class="identifier">control_callback</span></code></a> will be
                invoked for each control frame.
              </li>
<li class="listitem">
                For each received ping frame, a pong frame will be automatically
                sent.
              </li>
<li class="listitem">
                If a close frame is received, the WebSocket close procedure is performed.
                In this case, when the function returns, the error <a class="link" href="../../boost__beast__websocket__error.html" title="websocket::error"><code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">closed</span></code></a> will be indicated.
              </li>
</ul></div>
<p>
            Pong frames and close frames sent by the implementation while the read
            operation is outstanding do not prevent the application from also writing
            message data, sending pings, sending pongs, or sending close frames.
          </p>
<h7><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload2.h2"></a>
            <span class="phrase"><a name="beast.ref.boost__beast__websocket__stream.async_read_some.overload2.parameters"></a></span><a class="link" href="overload2.html#beast.ref.boost__beast__websocket__stream.async_read_some.overload2.parameters">Parameters</a>
          </h7><div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                    <p>
                      Name
                    </p>
                  </th>
<th>
                    <p>
                      Description
                    </p>
                  </th>
</tr></thead>
<tbody>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">buffers</span></code>
                    </p>
                  </td>
<td>
                    <p>
                      A buffer sequence to write message data into. The previous
                      contents of the buffers will be overwritten, starting from
                      the beginning. The implementation will make copies of this
                      object as needed, but but ownership of the underlying memory
                      is not transferred. The caller is responsible for ensuring
                      that the memory locations pointed to by the buffer sequence
                      remain valid until the completion handler is called.
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">handler</span></code>
                    </p>
                  </td>
<td>
                    <p>
                      The completion handler to invoke when the operation completes.
                      The implementation takes ownership of the handler by performing
                      a decay-copy. The equivalent function signature of the handler
                      must be:
                    </p>
<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span>
    <span class="identifier">error_code</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">ec</span><span class="special">,</span>       <span class="comment">// Result of operation</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_written</span>   <span class="comment">// Number of bytes written to the buffers</span>
<span class="special">);</span>
</pre>
                    <p>
                      Regardless of whether the asynchronous operation completes
                      immediately or not, the handler will not be invoked from within
                      this function. Invocation of the handler will be performed
                      in a manner equivalent to using <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">post</span></code>.
                    </p>
                  </td>
</tr>
</tbody>
</table></div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie
      Falco<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="overload1.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_read_some.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../write.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>
